High energy electrochemical batteries employing alkaline or earth alkaline metals as the active material in the anode require the use of non-aqueous, aprotic solvents for the preparation of the electrolyte. Thus typically in lithium anode based primary and secondary batteries it has been traditional to employ aprotic solvents such as cyclic ethers or esters such as methyl tetrahydrofuran (MTHF) and propylene Carbonate (PC). Recently, a new class of totally inorganic electrolytes has been proposed by B. F. Koslowski in X-Ray Investigations of Solvates of the type MALCL.sub.4 /SO.sub.2, Ph.D. Thesis, University of Hannover, Germany, 1989. This class is based on complexes of salts of Lewis Acids with sulfur dioxide. Prominent examples of these electrolytes are LiAlCl.sub.4.3SO.sub.2 all the way up to LiAlCl.sub.4.6SO.sub.2. These new inorganic electrolytes offer substantially higher conductivities of the order of 60 to 100 mS/cm compared to the typical values of 5-10 mS/cm obtained with organic solvents. These new electrolytic systems are more stable than organic electrolytes and less susceptible to side reactions during overcharge or overdischarge of a battery as it is being cycled.
This new class of electrolytes, because of its substantially greater conductivities and greater stability against electrochemical side reactions, offers new design and development possibilities for high energy batteries based on alkaline and earth alkaline earth anodes. Nevertheless, there exists several problems in their preparation, storage and use. Though the complex with 3SO.sub.2 is stable at 1 atmosphere and at room temperature when first prepared, within a short time it has a tendency to freeze with a slight decrease in the SO.sub.2 ratio, which typically is from 3.0 to 2.7. Once the electrolyte freezes there is a dramatic drop in cell conductance and the battery can no longer perform satisfactorily. This crystallization is readily seeded by the vessel walls and many metal and plastic materials in contact with the electrolyte as well as by the electrodes. It is only a matter of time when freezing occurs as it can happen within minutes, hours or weeks. If one goes up to higher contents of SO.sub.2, and is able to control the high vapor pressure, for instance for LiAlCl.sub.4.6SO.sub.2, the freezing tendency is decreased, although not eliminated once the material is depressurized. Furthermore, working with pressurized electrolytes presents serious obstacles in electrolyte and battery preparation and storage.